A Texas mother recently gave birth to two sets of identical twins — four boys, all conceived at the same time.

The mother, Tressa Montalvo, 36, told ABC News that she and her husband Manuel, 43, were trying to give their two-and-a-half year old only one baby brother or sister, but ended up with four. The parents named the boys with A-B-C-D theme: Ace, Blaine, Cash and Dylan.

Ace and Blaine shared one placenta during the pregnancy, Cash and Dylan shared the other.

Identical twins are created when one fertilized egg splits into two embryos, which happens in about 2 percent of all pregnancies. The chance of that happening twice, and at the same time, is about a one in 10,000 chance if the parents undergo in vitro fertilization, according to Dr. James Grifo, the director of the NYU Fertility Center.

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“This could also occur in a natural conception, but the chance of that is much [rarer],” Grifo told ABC News. Tressa said that they did not undergo in vitro fertilization or use any drugs to help her get pregnant.

“No fertility drugs were used. We planned the pregnancy — I guess we just succeeded a little too much!”

The boys made it to 31 weeks and were born on Valentine’s Day via cesarean section. They weighed between 2 pounds 15 ounces and 3 pounds, 15 ounces. Having multiple babies at one time does make the pregnancy much more dangerous for all of the babies, but as of now, the four boys are alive and being cared for at The Woman’s Hospital of Texas in Houston.

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“Having multiples certainly adds risk to a pregnancy in and of itself,” said Dr. Kimberly Gesci, an obstetrician at UH Case Medical Center in Cleveland, Ohio to ABC News. “One of the biggest risks is preterm delivery and growth restriction.”

Though they more than doubled the size of their family this last week, the Montalvos say they would still like to try for another baby.